My U.S. Pat. No. 4,271,119, issued June 2, 1981, is directed to a liquid transport device which, by means of a downstream diverting aperture in a wall member of a first capillary zone, provides capillary flow into a second capillary zone extending from that wall member. Because of the shape of the diverting aperture, liquid is diverted into the second zone from the first zone before the liquid flow of the first zone completely surrounds the diverting apertures. Failure to achieve flow into the second zone before the aperture is surrounded produces air entrapment, so that subsequent flow into the second zone is prevented.
Such a device has provided very successful diversion of capillary flow of liquid into the noted second zone, and has proved to be highly useful as an ion bridge for potentiometric test elements containing ISE's.
Notwithstanding the success of that device, there remained some aspects for improvement. For diverting apertures having a transverse flow-through area greater than about 0.2 mm.sup.2, the shape of the diverting aperture was critical--the aperture had to be considerably longer than wide, that is, with a length to width ratio of preferably between about 2.5 and about 10.0. In other words, the width dimension was no greater than 0.4 that of the length dimension. Such width-to-length relationships excluded circularly shaped apertures.
It would be advantageous to provide such a device wherein the diverting aperture is both circular in shape and has a flow-through area greater than about 0.2 mm.sup.2. Such circular apertures are the simplest to manufacture.